The present invention relates to suspended, enclosed structures providing a workplace beneath bridges, and the like. More specifically, the invention relates to a combination of elements which are temporarily mounted upon bridges or other structures while work is performed on substructure thereof to provide a thoroughly safe support for workmen, as well as a cost-effective, environmentally acceptable workplace.
In performing tasks such as sandblasting, painting, structural repairs, etc. upon substructure of existing bridges and other structures, it is necessary to provide a platform of some type to support the persons performing the task. Traditionally, such platforms have been provided by temporarily erected scaffolding or other such structure supported on the ground, etc. beneath the bridge, or suspended in some fashion from the bridge. Provisions must be made, of course, to enhance the safety of such workplace supports, which may require workmen to wear safety belts or tethers and the provision of suitable guard railings, as well as ensuring adequate load-bearing capabilities and structural stability of the supports.
More recently, environmental protection standards have been imposed on the performance of some types of work associated with renovation and repair of bridges, viaducts, elevated highways, etc. These standards may require, for example, that potentially harmful or toxic substances generated during performance of the work be prevented from entering the atmosphere, leaching into the soil, or being deposited in surface or ground water or upon other objects. Meeting such standards often involves constructing a complete enclosure about the workplace, and maintaining the interior of such enclosure at a subatmospheric pressure.
Recent examples of enclosed workplace supports for use in such applications include those disclosed in U.S. Pat. No. 4,854,419, issued Aug. 8, 1989 to Lyras et al, and U.S. Pat. No. 5,011,710, issued Apr. 30, 1991 to Harrison. The structures of both of these patents are in the nature of enclosed modules suspended by trolley systems for movement laterally and/or longitudinally of the bridge substructure as work progresses. Government regulations and/or laws require that workmen wear suitable safety belts while positioned on mobile workplace supports. This adds to the time and cost of the job, as well as hampering freedom of movement. Also, construction of these mobile supports requires fabrication of many specialized components and/or substantial modification of existing elements. Furthermore, the supports can be mounted only upon certain types of existing bridge structures. Substantial time and costs are involved in erecting and removing these workplace supports.
It is an object of the present invention to provide a support for workmen performing tasks on substructure of an existing bridge, or the like, which effectively eliminates the possibility of a workman falling while positioned on the support.
It is another object to provide an improved, fully enclosed workplace support which complies with all current environmental protection standards regarding emission and containment of toxic or otherwise prohibited substances.
A further object is to provide an enclosed workplace support for temporary installation in fixed relation to existing structures such as bridges which is relatively fast and economical to install and remove.
Still another object is to provide an enclosed, suspended workplace support for performing tasks on substructures of bridges, and the like, which has a high load-bearing capacity, yet adds little wind load to the structure to which it is attached.
A still further object is to provide a support system for workmen which is comprised of a combination of elements most of which are readily commercially available, without substantial modification.
An additional object is to provide an enclosed workplace having a relatively small volume compared to the available work area.
In a more general sense, the object of the invention is to provide a novel and improved, fully enclosed, suspended workplace for installation upon and removal from bridges and other such structures.